Strategies for finding a bandwidth-optimal topology for impedance matching

When searching for an impedance matching circuit yielding the maximum bandwidth with certain number of matching elements, the choice of the correct topology is crucial. Compared to optimal two-element (L-section) matching, the improvement of bandwidth provided by a third element can be anything from negligible to significant. In this paper, two approaches for finding an optimal three-element matching circuit are proposed. The first method is a simple optimization based search for promising matching topologies. The second method systematically searches the optimal matching topology and analyzes the bandwidth provided by the alternatives. Numerical results with example real-life loads are presented to demonstrate the importance of the topology choice in impedance matching.